Process for exchanging cations



Patented Jan. 7, 1941 UNITED STATES PATENT OFFICE Griessbach, Wolfen,

Kreis Bitterfeld, and

Walther Siitterlin, Bitterfeld, Germany, assignors to I. G.'Farbenindustrle Aktiengesellschaft, Frankfort-on-the-Main, Germany NoDrawing. Application May 18, 1939, Serial No. 274,402. In Germany July14, 1936 2 Claims.

This application is a continuation in part of our application Ser. No.152,784, filed July 9,1937.

Our present invention relates to a process for exchanging cations inaqueous solutions. Further 5 objects of our invention will be seen fromthe de-.

tailed specification following hereafter.

It is well known in the art that condensation products of aldehydes andpolyhydroxybenzenes may be used as cation exchangers. Correspondingcompounds made from'monohydroxybenzene and its homologous compounds arenot applicable for this purpose.

Now we have found that cation-exchangers of outstandingly goodproperties are producible from monohydroxybenzene, its homologouscompounds or its alkali metal salts, if acid groups are introduced intothe molecule by a suitable treatment with sulfites, bisulfites or $02.These products have nothing in common with the well known artificialtanning agents made from hydroxybenzene-aldehyde condensation products,since according to our present invention the condensation andacidification is carried out under such conditions that water-insolubleproducts are formed. By a suitable adjustment of the amounts of sulfiteand aldehyde the desired insoluble reaction products are formed in anycase, the most suitable amount to employ with the particularmonohydroxybenzene being easily determinable by a few simple comparativeexperiments.

The formation of a resin even occurs if 0.? mol. S03" are added per mol.hydroxybenzene, the condensation products becoming insoluble in water asnecessary for exchanging bodies by aftertreatment with, for instance,hydrochloric acid. This after-treatment with an acid is suitablelikewise in the production of resins having a somewhat lower acidcharacter. The treatment with a sulfite can be carried out during orafter the formation of the monohydroxybenzene-aldehyde resins, themanufacture of the endproducts being possible even when carrying out thecondensation and treatment with a sulfite in-several stages. We assumethat in our process w-sulfonic acids of the hydroxybenzene are formed,and, in fact, these w-sulfonic acids may be used per se as startingmaterials.

The drying of the primary formed resinous jellies is carried out in sucha way, that the gel structure is maintained.

The examples following hereafter serve to illustrate our invention, theparts being by weight, if not indicated otherwise.

Example 1.216 parts of meta-hydroxytoluene and252 parts of sodiumsulfite are heated for 8 hours to 100 C. together with 500 parts ofwater and 200 parts of a formaldehyde solution of 30 per cent strength.Then a further amount of 650 parts of meta-hydroxytoluene dissolved withparts of caustic soda in 250 parts of water is added to the reactionmixture together with 800 parts of a formaldehyde solution of 40 percent strength. After boiling for about 1 hour, the solution solidifiesto a solid gel which is dried at 80 C. After reduction to small piecesit is a valuable product for exchanging cations with a capacity byweight of 2.1 per cent (calculated on CaO).

Example 2.-1500 parts of a resin disintegrated to form grains of 0.5 to2 mm. diameter and produced by condensation of a solution of 1880 partsof hydroxybenzene, 200 parts of caustic soda in 3000 parts of watertogether with 880 parts of a 7 formaldehyde solution of 40 per centstrength are boiled for an hour under reflux together with a solution of256 parts of sodium sulfite and 200 parts of a solution of formaldehydeof 30 per cent strength in 2000 parts of water. Then the resin isseparated from the solution and washed with water. The material exhibitsgood properties of exchanging cations.

Example 3.-A solution of 1500 parts of hydroxybenzene and 504 parts ofsodium sulfite in 1500 parts of water and 400 parts of a formaldehydesolution of 30 per cent, strength are boiled under reflux for'10 hours.After addition of a further amount of 600 parts of a formaldehydesolution of the same concentration the solution solidifies when heatedfor 20 hours to 95 to 100 C. The product thus obtained is dried at to C.andwhen reduced to small, pieces is an excellent cation-exchangingmaterial with a capacity by weight of 3.1 per cent. (calculated on CaO).

Example 4.376 parts of hydroxybenzene are introduced into a solution of504 parts of sodium sulfite in 1000 parts of water and 120 parts of aformaldehyde solution of 30 per cent. strength and then boiled underreflux for 12 hours. In the solution thus obtained there are dissolvedat to C. a further amount of 1128 parts of hydroxybenzene dissolved in540 parts of water and parts of caustic soda and then at boilingtemperature, while stirring, 600 parts of a formaldehyde solution of 30per cent. strength are introduced within an hour. Boiling is 0011-)tinued for about 3 hours, the solution solidifying under formation of agel which is reduced to small pieces after having been allowed to standfor 15 hours at 100 C. and is dried at 75 to 80 C.

When using the exchange-bodies produced according to'this example, forremoving the hardness of a tap water of 22 hardness (German degree), thematerial takes up 2.7 per cent. of

CaO calculated on its own weight.

Example 5.-940 parts of hydroxybenzene and 340 parts of sodium sulfiteare dissolved in 1400 parts of water and 1700 parts of a formaldehyde.

hardness of water, shows a capacity of about 3" per cent. by weight(calculated on CaO). 7

Example 6.--940 parts of hydroxybenzene' are boiled for 10 hours underreflux with a solution of 1260 parts of sodium sulfite in 2500 parts ofwater and 1000 parts of formaldehyde solution of '30 per cent. strength.To this solution there is added a further amount of 400 parts ofhydroxybenzene and 2000 parts of a formaldehyde solution of 30 per cent.strength and the' whole is heated for 24 hours to 100 C. During thistime the solution solidifies and becomes hard. .After drying at 80 C.and comminution the resin is boiled for 2 hours with hydrochloric acidof about 20 per cent. strength. It is separated from the liquid andwashed until neutral. It may be used as a cation-exchanging body in aneutral or acid medium.

Example 7.-984 parts of hydroxybenzene, 1208 parts of sodium sulfite,2400 parts of water and 1760 parts of a formaldehyde solution of 30 percent. strength are heated for hours to 100 C. 1000 parts ofhydroxybenzene and 4600 parts of a formaldehyde solution of 30 per cent.strength are added at 60 C. The mixture gets warm and solidifies aftersome boiling to a jelly which after standing for 24 hours is dried at100 C. and comminuted to pieces of 0.3 to 1.5 mm. diameter. One part byvolume of this material is treated with one part by volume of sulfuricacid (monohydrate) for about hours. When mixing the components thetemperature raises to about 110 C. The resin washed with water untilneutral is an excellent cation-exchanger which is resistant to hot waterand weak alkaline solutions, the capacity by volume being 0.8 to 0.9 percent. (calculated on CaO) Example 8.1000 parts of hydroxybenzene, 1260parts of sodium sulfite. 2000 parts of water and 1200 parts of aformaldehyde solution of 30 per cent. strength are heated for 6 hours to100 C.

Further 880 partsof hydroxybenzene and 2600 parts of a formaldehydesolution of 30 per cent. are added. After boiling for 20 hours thesolution solidifies to a jelly which is dried at 100C. until the weightis constant. After comminution to pieces of 0.3-1.5 mm. diameter thematerial is boiled for 2 hours with hydrochloric acid 1 1.

The capacity by volume of the resin is 1.7 per cent. (calculated onCaO).

It is obvious that our invention is not limited to the foregoingexamples or to the specific details given therein. Various modificationsand changes indetails are considered to be within the spirit of thisinvention and the scope of the claims following hereafter. Thus, forinstance, w-Slllfonic acids of monohydroxybenzene may be prepared in a.separate process and used as starting materials. This variation is notlimited to the use of w-methylene sulfonic acids, but here likewise thehomologous compounds derived from another alkyl radicle may be chosenfor the resinification. The quantities of the reacting substances may bevaried within certain limits, whereat care is to be taken that theendproduct is insoluble in water, an increased water-solubiL ity beingcaused by a plurality ofSO3H-groups introduced into the molecule. Aspointed out, resin formation occurs even if 0.7 mol. S03" are present inthe reaction mixture per mol. hydroxybenzene, but generally, we preferto use no more than about 0.5 mol. S03". In order to diminish theswelling of the resins when contacted with water, an after-treatmentwith an acid while heating, for instance, with hydrochloric acid,sulfuric acid or phosphoric acid is suitable.

The mentioned exchanging resins may be used as neutral or hydrogenexchangers for purifying water, recovering metals, organic bases, etc.

What we claim is:

1. A process for exchanging cations in aqueous solutions which comprisessubjecting the liquid to the action of a waterinsoluble monohydricphenol-formaldehyde resin containing w-sulfonic acid roups charged withthe desired cations.

2. A process for exchanging cations in aqueous solutions which comprisessubjecting the liquid to the action of a waterinsoluble monohydricphenol-formaldehyde resin containing w-SLllfOlliC acid groups, saidresin having been previously treated with a hot inorganic acid andcharged with the desired cations.

HANS WASSENEGGER. ROBERT GRIESSBACH. WALTHER SUI'IERLIN.

